Circuit breaker



' 2 1941- L. PIERCE ETAL 2,265,004

CIRCUIT' BREAKER Filed Jan. 28, 1938 3 Sheets-Sheet l ATToRNE" Dec. 2, 1941. L, PIERCE ErAL CIRCUIT BREAKER Filed Jan. 28, 1938 3 Sheets-Sheet 2 WITNEssEs:v

ATTORN 2, 1941. L. PIERCE ErAL CIRCUIT BREAKER Filed Jan. 28, 1938 3 Sheecs-SheelI 3 mw MW.

WITN ESESz ATTORNEY I Patented Dec. 2, 1941 CIRCUIT BREAKER Lawrence Pierce, Edgewood, and Stephan Miller, Wilkinsburg, Pa., assignors to Westinghouse Electric & Manufacturing Company,

East

Pittsburgh, Pa., a corporation of Pennsylvania Application January 28, 1938, Serial No. 187,446

24YClaims. (Cl. 200-116) The invention relates to circuit breakers in general and more particularly to circuit breakers for controlling and protecting lighting and motor circuits.

An object of the invention is the provision of a circuit breaker embodying an improved operating mechanism that is manually operable to effect movement of the switch member to open and to closed circuit position with a snap action, and automatically operable by current responsive release means in response to predetermined conditions to effect movement of the switch member to a tripped open circuit position with a snap action irrespective of the position of the manual operating member.

Another object of the invention is the provision of a circuit breaker embodying an improved operating mechanism and mounting means for the movable switch member whereby the switch member is moved in a substantially straight line path during normal switching operations and in a different; path during a tripping operation.

Another object of the invention is the provision of a circuit breaker embodying an improved mounting means for the movable switch member whereby it is supported and guided for free rolling movement to its different actuated positions.

Another object of the invention is the-provision of a circuit breaker in which the movable switch member and the current responsive release means are detachabiy mounted on the support for the operating mechanism to facilitate asmbly and disassembly of the parts.

Another object of the invention is the provision of a circuit breaker in which the current responsive release device is adjustably mounted for movement relative to the breaker mechanism so that the trip element of the release device can be set in the proper position relative to the means which transmits its movement to the latch means of the breaker mechanism. v

Another object of the invention is the provision of a circuit breaker in which the contact means, switch member operating mechanism and the current responsive release means are The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. `The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will best be understood from the following detailed description thereof when.

read in connection with the accompanying drawings, in which:

Figure 1 is a plan view of a circuit breaker constructed in accordance with the invention, the cover for the casing having been removed to show the arrangement of the various parts.

Fig. 2 is a vertical sectional View of the breaker illustrating the mechanism and contact means in closed circuit position.

Fig. 3 is a vertical sectional view of the breaker, the mechanism and -contact means being shown in elevation and in the tripped open position following a tripping operation.

Fig. 4 is a verticalsectional view similar to Fig. 2 illustrating the mechanism and contact means in the manually opened position.

Fig. 5,y is a. vertical sectional view of the circuit breaker taken substantially on the line V--V of Fig. 4 and looking in the direction of the arrows.

Fig. 6 is afragmentary view, partly in section, illustrating the current responsive release devices and a portion of thel latching means of the breaker, and

Fig. '7 is a fragmentary view, partly in section,

illustrating the mounting arrangement of the current responsive release devices.

Referring to the drawings, the circuit breaker comprises a channel shaped base 9 of sheet metal construction provided with a frame Il for supporting the circuit breaker unit. The base 9 and circuit breaker unit are removably mounted in the sheet metal enclosure formed by a generally rectangular casing I3 and a cooperating removable cover I5.

'I'he base 9 is removably mounted on the bottom wall of the casing I3 by means of a hookshaped lug I'I struck up from the bottom of the mounted on a common support and arranged in a novel manner to reduce the space occupied. by the breaker and provide a compact structure.

Another object of the invention is the provision of an enclosed circuit breaker or switch mounted in a casing having a removable cover which can be locked in closed position, with a normally inoperative safety locking means disposed within the casing which is manually settable to lock the operating member in one of its operating positions. I

Another object of the invention is the provision of an improved circuit breaker las described above that is simple, safe and reliable in operation, and inexpensive to manufacture and service.

casing which hooks over the end edge of a notch formed in one end of the base 9, as shown in Figs. 2 and 4, and by a fastening screw I9 which fastens the opposite end of the base 9 to a raised boss 2| formed integral with the bottom wall of the casing I3.

The casing I3 is provided with integrally formed perforated bosses 23 adjacent the corners for mounting the breaker on a panel or other form of support. Suitable knockouts may be provided in the walls of the casing for accommodating lead-in conductors for connecting the breaker in an external circuit.

The c ver-I5 is Divotally mounted on the casing y hinges 25 and is adapted to be latched in closed position covering the casing by means of a latch member 21 which is pivotally mounted inside the cover I and biased by a spring 29 to latching position in which its hooked end engages the edge of an opening 3|` formed in the end wall of the casing I3. The latch 21 is provided with a U-shaped bail 33 which projects through an opening in the end wall of the cover I5 and serves as an operating member for the latch which may be pushed in to release the latch to permit opening of the cover I5. A padlock or other form of locking means 35 may be provided for engaging the bail 33 of the latch member 21 to lock the cover in closed position. The cover I5 is provided with a well 31 having an elongated opening 39 through which projects the operating handle of the circuit breaker.

The circuit breaker unit comprises, in general, a movable switch member indicated generally at 4| 'for controlling the contact means of the breaker, an'operatinvg mechanism indicated generally at 43 for operating the switch member to open and to closed circuit position, and a pair of current responsive release devices indicated generally at 45 (Fig. 1), each of which is operable in response to predetermined overload conditions to cause the operating mechanism to move the lswitch member to a tripped-open circuit position.

The contact means of the breaker comprises a plurality of sets oi spaced stationary contacts 41 and a plurality of cooperating movable bridging contact members 49, which serve to bridge the stationary contacts 41 and close the circuit in the closed position oi' the breaker. u

The stationary contacts 41 of each set are secured in spaced relation on the opposed ends of a pair of conducting strips 5| and 53 which are mounted in vertical alignment and in spaced transverse relation on a transversely disposed insulating block 55, the strips being secured to the block by means of the fastening bolts 51. 'I'he insulating block 55 is removably-mounted on the base 9 yadjacent the upper end thereof by means of a pair of bolts 59 (Fig. 1) which pass through the block 55 and engage in threaded -openings provided in the base 9. 'I'he upper or outer conducting strips 5| are bent at right angles to prolect beyond the block 55 and are provided with thegcontact member 4,9,- which engage .in guide slots159 provided therefor in the sidewalls of the netic material carried in an opening provided` therefor in the insulating block 55 adjacent the spaced stationary contacts 41. The resulting single arc described above which plays between the opposed ends of the conducting strips 5| and 53 sets up a magnetic-flux in the plates 15 which quickly draws the arc into the plates where it is immediately cooled and extinguished in a well known manner.

The contact carrying frames 55 and the movl -able bridging contact members 49 carried thereby are mounted in spaced transverse relation on a cross bar 11 of insulating material whichis secured intermediate its ends to the outer end of the movable switch member 4| .by a pair of screws 19 (Fig. 1).

The movable switch member 4| is constructed of sheet metal andA formed to provide a pair of spaced parallel legs 9| which are connected at their lower edges by a pair of integral cross braces 93. The outer ends of the legs 8| of the switch member 4| are bent at right angles and provided with threaded openings for receiving the fastening screws 19 which serve to secure the cross bar 11 to the switch member 4|. The legs 9| of the switch member 4| extend into the space between the side Walls of the main frame I I and the lswitch i member is detachably mounted for movement on lto contact" carrying frame 55. 'Each contact nlnember 491s biased toward its corresponding pair of stationary'contacts 41 by means'ofa coil compression spring 1| interposed between the back ofthe contact member 49 and the contact carrying frame 55.

'I'he particular mounting of the stationary contacts 41 cooperates with the loop-shaped construction of the movable bridging contact member 49 to provide sharp bends in the path of the 2current .iiowing through the stationary contacts ber separates' from the stationary contacts 41,

the frame by means o! afroller which is carried by a fixed shaft 91 extending transversely 'between the side walls of the framel I I. the legs 9| of the switch member 4| being provided with elongated parallel guide slots 99 for engaging the roller 95. 'I'he slots 99 at their inner ends each4 open to the upper edge of the legs 9|, as

indicated at 9| (Figs. 2 and 4), so that the switchl member 4| is removably 'mounted on the roller 95.

The operating mechanism` 43 is supported on the U-shaped main framey II and comprises, in general, a releasable carrier 93 which is pivotally mounted between the side walls of the main frame by means of a pivot pin 95,a pair of actuating links 91 pivotally connected at their upper 91 to the switch member 4|, and the upper endsof the springs are connected to the bight portion of a U-shaped operating member |95 which is pivotally mounted on a pair of lugs |91 struck out from the side walls of the frame Il. The operating member |95 is retained in pivotally mounted position on the frame by means of 'the tension ofthe overcenter springs |93.

The carrier 99 is releasably held in a normal latched position, as shown in Fig. 2, by means of a latch |99 which is pivotally mounted on a pivot pin III which extends transversely between the side walls of the frame I I, the free end of the carrier 93 being provided with a latch nose I I3 which is normally engaged under the edge of an opening |I provided in the latch member |09. The latch member |09 is releasably retained in latching position as shown in Fig. 2 by a second latch member I |1 which is pivotally mounted on a pivot pin I I9 extending between the side walls of the main frame II. The latch member II1 is biased in a clockwise direction about the pivot pin II9 by means of a coil compression spring |2I. The lower end of the latch member |09 normally abuts the free end of the second latch member |I1 so that the latch member II1 normally prevents counter-clockwise or releasing movement of the main latch |09. A lug is struck inwardly from the lower end of the latch |09, which engages the upper side of the second latch I|1 to prevent clockwise movement of the second latch H1 when the latches are engaged, as shown in Fig 2.

The upper end of the operating member |05 is provided with an operating handle |23 which extends through the opening 39 in the cover l5, and an arcuate shield which serves to close the opening 39 in all positions of the operating member.

The U-shaped main frame I| is mounted centrally on the base member 9 adjacent one end thereof by means of a pair of rivets |21 so that the frame and mechanism carried thereby are disposed substantially in alignment with the contacts which form the center pole of the circuit breaker unit, as best shown in Fig. l, and the entire operating mechanism, with the exception of the manual operating member |05 and its handle |23 and shield |25, is disposed between the side walls of the frame I I. If desired, the frame II may be formed integral with base 9 instead of as a separate member secured to the base.

The pair of current responsive release devices 45 are mounted on opposite sides of the U- shaped main frame II and each comprises, in general, an insulating block |29 having a recess in which is mounted a bimetallic thermal disk |3| and a heating coil |33 (Fig. 6), The bimetal disk |3| is of the type which has a preformed deformation that moves from an original position to an inverted position, with a snap action, when heated a predetermined amount and which returns to its original position with a snap action when cooled below a predetermined temperature. The edges of the disk |3| are clamped in a iixed position between the in-turned flanges of a pair of interiitting cylinders |35 and |31 which are mounted within the recess in the insulating block |29. The heater coil |33 is disposed within the cylinder |35 in spaced relation to the bimetallic disk |3| and is removably electrically connected by screws |40 to a pair of terminal strips |39 and I4| (Fig. l) secured to the upper edge of the insulating block |29. The terminal strips |39 and I4| are provided with terminal screws |43 for connecting the heater coil |33 in circuit with one of the pairs of stationary contacts and one of the terminals of the breaker. A diaphragm |45 is interposed between the heater coil |33 and the bimetal disk |3| and the diaphragm has a plurality of elongated openings |46 (Fig. 3) for permitting the radiated heat of the heater coil to pass directly to the Surface 0f the disk. The diaphragm |45 is rigidly secured in any suitable manner as by brazing or welding Li f) latches |I1 and |09.

to the cylinder |31, which is in turn rigidly secured within the cylinder |35 in any suitable manner. n

The bimetallic disks |3| of the current responsive release devices are adapted when heated a predetermined amount to actuate the latch member I1 to its released position to eiect a tripping operation of the circuit breaker. A pair of angleshaped tripping members |41 (Fig. 6) are loosely mounted for rocking movement or partial rotation in openings provided therefor in the opposite side walls of the main frame I Each of the tripping members |41 has the reduced leg |49 which passes through the opening for engaging the upper surface of the latch member II1, as best shown in Figs. 2 and 6. The angular portion |5I of each trip member |41 which is disposed outside of the frame II is provided with a rectangular opening for loosely engaging a smaller rectangular projection |53 of an insulating button |55 which serves to operatively connect the trip member |41 to its corresponding bimetal disk |3|. The trip member |41 is adapted to be partially rotated or rocked inwardly about the lower edge of the opening provided therefor in the frame II as a fulcrum when the bimetallic disk is snapped to its inverted position by an overload. The side of the button |55 opposite the trip member 41 is provided with a circular recess |51 for receiving the end of an adjusting screw |59 threaded through the center portion of the diaphragm |45. The adjusting screw |59 carries a collar |64 which engages the center portion of thel disk |3|, and a lock nut |62 for locking the screw in adjusted position. The screw |59 is turned to adjust the tripping point of the disk |3|. The trip members |41 are removably inserted in the openings provided therefor in the side walls of the frame II and the insulating buttons |55 are lioated between the trip members |41 and the current responsive bimetallic disks |3|, thus facilitating assembly and disassembly of these parts as well as the current responsive release devices 45.

Each current responsive release unit 45 is detachably mounted on the frame II by means of a plurality of screws |56 which pass through countersunk openings |58 (Fig. '7) in the block |29 and engage threaded openings provided in a side wall of the frame II. Each screw |56 is encircled by a coil spring |60 which is interposed between a shoulder formed in the screw opening |58 of the block |29, and the sidewall of the frame II. so that the springs |60 `\bias the block |29 away from the side wall of \the frame against the heads of th'e screws |56. The screws |56 are adjusted during the assembly 0f the breaker to properly position the bimetal disk |3| carried by the block |29, so that when the disk |3| snaps from its original position to its inverted position, it 'effects release of the This particular mounting arrangement of the current responsive release devices 45 in addition to detachably mounting the devices, provides a means for properly. positioning `the bimetal disks |3| relative to buttons |55 and trip levers |41, so as to compensate for any slight 'manufacturing inaccuracies of the various parts. By reason of the novel mounting arrangement of the current responsive nrelease units 45, greater tolerances are permitted in the manufacture of the various parts so that the production cost is materially reduced. After the current responsive release units have been ad- Justed to their proper positions relative to the frame by means of the screws |56, the enlarged openings in the blocks for accommodating the heads of the screws may be lled with a suitable Ysealing wax.

It will be noted that the current responsive release devices 45, together with the tripping members |41 and the insulating buttons |55, are mounted within the width required for the contact means of the outer poles of the circuit breaker, thus providing a very compact circuit breaker structure which occupies a minimum amount of space.

An insulating block |6| is mounted by means of a screw |53 (Fig. 1) on the end of the base vopposite the end which supports the stationary contact means, and this block serves to support the center pole end terminal member |65 and its terminal screw |61.

The electrical circuit through the two outer poles of the circuit breaker are identical and 'each extends from the upper end terminal strip through the upper stationary contact 41, bridging contact member 49, lower stationary contact 41, conducting strip 53 througha flexible insulated conductor |69, to the terminal strip |39 of the current-responsive release device 45, through the heater coil |33 of the release device to the opposite terminal member I 4I. The circuit for the center pole of the breaker extends from the upper terminal strip 5| through the upper stationary contact 41 carried thereby, the movable bridging contact member 49 and lower stationary contact 41 for the center pole through the conducting strip 53 and a flexible insulated conductor |1| directly to the center pole end terminal member |65.

The operation of the .circuit breaker is briey as follows: With the parts in the position shown in Fig. 2, let it be assumed that it is desired .to manually open the circuit. The operating member |05 is moved in a counter-clockwise direction by the handle |23 from the position shown in Fig. 2 to the position shown in Fig. 4. During this movement of the operating member, the line of action of the overcenter springs 03 is shifted to the left of the pivot pin 99 to effect movement of the actuating links 91 and the switch member 4| with the movable bridging contact members 49 carried thereby to open circuit position with a snap action. The manually opened position of the breaker is illustrated in Fig. 4.

- tion shown in Fig. 2. During the clockwise movement of the operating member |05, the line of action of the overcenter springs |03v is shifted to the right of the pivot pin 99 which carries the links 91 to effect movement of the actuating links 91, the switch member 4| and the movable bridging contact members 49 carried thereby to closed circuit position with a snap action. The roller 85 permits the switch member 4| to be rolled freely to onen and to closed position, and also serves to guide the switch member so that it is moved in a substantially straight line path during normal switching operations.

When an overload of predetermined magnitude and durationoccurs in the circuits of either of the two outer poles of the circuit breaker. the corresponding birnetallic disk |3| of the current responsive release device 45 for the particular pole affected is heated by the current a suflicient amount to cause it to move from its original position to its inverted position with a. snap action. The movement of the bimetallic disk |3| to its inverted position moves the insulating button |55 inwardly to eiect inward rocking or inwardly directed partial rotation of the corresponding trip member |41 on the edges of the opening provided therefor in the side Walls of the frame It, to a tripping position. When the tripping member |41 is thus rocked to its tripping position, the leg |49 thereof is moved downwardly to eilect counter-clockwise rotation of the latch member ||1 about its pivot axis ||9. The down- Ward movement of the latch member ||1 effects release of the main latch member |09 and the latch member |09 is moved to its releasing position under the influence of the overcenter springs |03 to effect release of the carrier 93. When the carrier 93 is released, it is moved in a clockwise direction by the force exerted by the overcenter springs |03. This clockwise movement of the pivoted carrier 93 carries the pivot pin 99 to the right, as viewedin Fig, 2, across the line of ized closing of the circuit breaker.

action of the overcenter springs |03. As soon as the pivot pin 99 crosses the line of action of the overcenter springs, these springs act to move the switch member 4| to a tripped open circuit position, and the operating member |05 to an intermediate trip indicating position as shown in Fig. 3. The switch member 4| in moving to its tripped open position pivots in a clockwise direction about the rollerV and isthen rolled ty the force exerted by the springs |03 to open circuit position, as shown in Fig. 3.

Before the circuit breaker can be reclosed, it is necessary to reset the carrier 93 and the latches |09 and ||1 to their latching positions. In order to reset the mechanism, the operating member |05 is rotated in a counter-clockwise direction. During the resetting movement of the operating member |05, a projection |12 carried by the operating member engages and moves the carrier 93 in a counterclockwise direction. The counterclockwise movement of the carrier 93 causes the latch nose ||3 of the carrier 93 to engage the lower edge of the opening ||5 of the latch member |09 and move that member to its latching position. When the latch member |09 has thus been returned to its latching position, the second latch member ||1 is moved by the biasing spring |2| so that its end reengages the end of the latch member |09. When the operating member |05 is released following this resetting movement, the latch nose |3 is returned to its latching position in which it is engaged by the upper edge of the opening |5 of the latch member |09. The mechanism is nowcompletely reset and the circuit breaker can be reclosed by moving the operating member |05 in a clockwise direction to closed circuit position to close the circuit breaker in the manner previously described. y

A safety locking means is provided for locking the operating member |05 in open circuit position whenever it is desired to prevent unauthor- The locking mea-ns comprises a lever 13 (Figs. 1 and 5) which is pivotally mounted on a stud |15 carried by one of the legs of the operating member |05 within the casing. The lower end of the lever |13 is provided with an inwardly bent projection |11 which normally engages ari-opening provided therefor in the leg of the operating member |05. A coil spring |19 is mounted on the stud |15 between the enlarged end |8| thereof and the lever |13. The spring |19 serves to maintain the locking lever |13 in either its inoperative or operative position, depending upon the setting thereof. One of the side walls of the main frame is provided with an extension |83 (Fig. 2) having an opening |85 formed vtherein for receiving the inwardly projecting end of the locking lever |13 when that lever is set in locking position.

To lock the circuitI breaker in open circuit posltion, the cover is opened and the lever |13 is manually set with its inwardly projecting end |11 engaged in the opening |85 provided in the frame The cover I5 is then returned to closed position and locked in closed position by the padlock or other locking means 35. Under these conditions, it is impossible for any unauthorized person to move the operating member |05 away from its open circuit position.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details thereof may be made without departing from the spirit of the invention. It, is desired, therefore, that the language of the accompanying claims be given the broadest reasonable interpretation that is permissible in the light of the prior art.

We claim as our invention:

1. In a circuit breaker, a frame member, a switch member movable to open and to close the circuit, a movable carrier for said switch member, means for releasably restraining said carrier in an operative position, operating means including an overcenter spring for moving said switch member to open and to closed circuit position and for biasing said carrier to a released position, one of said members being provided with a guide roller and the other of said members with a guide surface for engaging said roller to guide said switch `member for rolling movement in a substantially straight line patli during normal switching operations, said carrier when released causing said operating means to move said' switch member to a tripped open circuit position.

2. In a circuit breaker, a frame member, a switch member movable to open and to close the circuit, a movable opening means forsaid switch member, means for releasably restraining said opening means in an operative position, operating means including an overcenter spring for moving said switch member to open and to closed circuit position and for biasing said opening means to a released position, one of said members being provided with a guide roller and the other of said members with a guide surface for engaging said roller to guide said switch member for rolling movement in a substantially straight line path during normal switching operations, said opening means when released causing said switch member to pivot on said roller and be rolled to a tripped open circuit position.

3. In a circuit breaker, a frame member, a switch member movable to open and to close the circuit, a movable opening means for said switch member, means for releasably restraining said opening means in an operative position, operating means including an overcenter spring for moving said switch member to open and to closed circuit position and for biasing said opening means to a released position, one of said members being provided with a guide roller and the otherA of said members with a guide surface for engaging said ,roller to guide said switch member for rolling movement in a substantially straight line path during normal switching operations: said opening means when released causing said switch member to pivot on said roller and be rolled to a tripped open circuit position by said operating means, and electro-responsive means operable in response to predetermined conditions to effect release of said opening means.

4. In a circuit breakera frame, a switch member movable to open and to close the circuit, a carrier pivoted on said frame, means for releasably restraining said carrier in an operative position, an actuating element mounted for movement on said carrier and connected to one end ,of said switch member, operating means includoperations, said carrier when released causing said switch member to pivot on said roller and be rolled by said operating means to a tripped open circuit position.

5. In a circuit breaker; a frame, a switch member movable to open and to close the circuit, operating mechanism carried by said frame and detachably connected to one end of said switch member for moving said switch member to open and to closed circuit position, said Aframe and said switch member being provided one with a guide roller and the other with a cooperating elongated roller receiving slot for'guiding said switch member for rolling-movement on said frame in a substantially straight line during normal switching operations, said slot having an opening for removably mounting said switch member on said frame.

6. In a circuit breaker, a frame, a switch member movable to open and to close the circuit, operating mechanism carried by said frame and detachably connected to one end of said switch member for moving said switch member to open and to closed 'circuit position, said frame and said switch member being provided one with a guide roller and the other with a cooperating elongated roller receiving slot for guiding said switch member for rolling movement on said frame in a substantially straight line during normal switching operations, said slot having an opening for removably mounting said switch member on said frame, and electro-responsive trip means operable in response to predetermined conditions to cause said operating mechanism to move said switch member to a tripped open circuit position.

'1. In a circuit breaker, a frame having side walls, a switch member carried by said frame movable to open and to close the circuit, operating mechanism carried by said frame between the side walls thereof operable rto move saidI switch member to open and to closed position, said mechanism' including means releasable to effect movement of said switch member to open position, a trip member extending through an opening in one of the side walls of said frame movable to a tripping position to effect release of said releasable means, and a trip element mounted outside said frame adjacent the side wall through which said trip member extends, operable in response to predetermined conditions to cause movement of said trip member to tripping position.

8. In a circuit breaker,\a frame having side walls, a switch member carried by said frame movable to open and to close the circuit, operating mechanism carried by said frame between the side walls thereof operable to move said switch member to open and to closed position, said mechanism including means releasable to effect movement of said switch member to open position, a trip member extending through an opening in one of the side walls of said frame movable to a tripping position to eect release of said releasable means, and a trip unit detachably mounted at the side of said frame adjacent the side wall through which said trip member extends, said unit including a resettabl trip element operable in response to predetermined conditions in the circuit to cause movement of said trip member to tripping position.

9. In a circuit breaker, a frame having side walls, a switch member carried by said frameand movable to open and to close the circuit, operating mechanism carried by said frame between the side walls thereof operable to normally move said switch member` to open and to closed position, said mechanism including means releasable to eiect movement of said switch 4member to open position, a trip member removably mounted in anv opening provided'in one of the side walls of said frame and having a portion extending into the space between the side Walls for engaging said releasable means, said Atrip member being movable to a tripping position to eiect ,release of said -releasable means, and a trip unit removably mounted outside said frame adjacent said side wall including an electro-responsive trip element operable in response to predetermined conditions to cause movement of said trip member to tripping position.

10. In a circuit breaker, a frame having side walls, a switch member carried by said frame and movable to open and to close the circuit, operating mechanism carried by said frame between the side walls thereof operable to normally move said switch member to open and to closed position, said mechanism including means releasable to effect movement of said switch member to open position,r an angle shaped trip lever removably and pivotally mounted on a side wall of said frame having a reduced arm extending through an opening provided therefor in said side wall for engaging said releasable means, said lever being pivotally movable onA an edge 4vof said opening to a tripping position to effect release of said releasable means, and a trip unit removably mounted outsidesaid frame adjacent said side wall including an electro-responsive trip element operable in response to predetermined condi-tions to cause rotation of said trip lever to its`tripping position, said trip unit when in mounted position serving to retain said trip lever in its mounted position on said side wall. 11. In a circuit breaker, a frame having side walls, a switch member carried by said frame leasable means, a trip unit removably mounted at the outer side of said side wall including a thermally responsive trip element heated in response to the current flowing in the circuit and operable in response to predetermined overload conditions to cause movement' of said trip member to tripping position and an insulating button loosely interposed between and connecting said trip member and trip element.

12. In a multipole circuit breaker, a base, a frame mounted on said base, a movable switch member carried by said frame, a transversely extending cross bar carried by said switch member, a plurality of contact members mounted in spaced relation on said cross bar, operating mechanism carried by said frame normally operable to move said switch member to open and to closed position, said mechanism including means releasable to effect movement of said switch member to a tripped open position, the width of said mechanism being less than the length of said transverse-cross bar, anda current responsive release device comprising a bi` metal trip element mounted at the side of said frame operable in response to predetermined conditions .to effect release of said releasable means.

13. In awmultipole circuit breaker, a base, a frame mounted on said base, a movable switch member carried by said frame, a transversely extending cross bar carried by said switch member, a plurality of contact members mounted in spaced relation on said bar, operating mechanism carriedby said frame normally operable to move said switch member to open and to closed circuit position, said mechanism including means releasable to eiect movement of said switch member and contact members to a tripped open circuit position, the width of said mechanism and frame being less than the length of said transverse cross bar, and a pair of current 'responsive release devices mounted onopposite sides of said frame and mechanism, each able means, said trip member being movable to'v a tripping position to effect release of said reincluding a bimetal trip element operable in response to predetermined conditions toeiect release of said releasable means.

14. In a. multipole circuit breaker, a base, a frame having side walls mounted on said base, a switch member detachably mounted on said frame for movement thereon, a transversely extending cross bar carried by said switch member outside said frame, a plurality of contact members mounted in spaced relation on said bar, op-,f/

erating mechanism carried by said frame between the side walls thereof normally operable to move said switch member and contact members to open and to closed-circuit position, said mech- 'anism including means releasable to effect movement of` said switch member and contact members to a tripped open circuit position, the width of said frame and mechanism being less than the length of said transverse cross bar, and a pair of current responsive release devices movably mounted on opposite sides of said frame each including a snap-acting bimetal'trip element operf able in response to predetermined conditions to effect/'release of said releasable means.

15.1 In a circuit breaker having an operating mechanism including a member releasable to effect opening of the circuit, and a latch means for releasably restraining said member, a trip unit lcarrying a snap-acting bimetal element which is operable in response to predetermined conditions to eivect release of said latch means, and means movable to cause movement of said trip unit which carries said element relative to said mechanism. v

16.In a c lrcuit breaker having an operating mechanism including a member releasable to effect opening of the circuit and latch means for releasably restraining said member, in combination, a current responsive release unit carrying a snap-acting bimetal element which is operable in response to predetermined conditions to eilect release of said latch means, means interposed between said bimetal element and said latch means for transmitting the movement of said bimetal element to said latch means, and means movable to cause movement of said trip unit which carries said element relative to said operating mechanism.

17. In'a circuit breaker having an operatingv mechanism including means releasable to effect opening of the circuit, a trip device including a trip element that is movable in response to predetermined conditions to effect release of said releasable means, said trip device being mounted for movement relative to the operating mechanism to permit accurate positioning thereof relative to the mechanism, and means for adjusting the trip characteristic of the trip element.

18. In an enclosed circuit breaker, an enclosure having an openable cover, means for locking said cover in closed position, a circuit breaker mounted within said enclosure having an operating mechanism including a movable operating member that is operable from outside said enclosure to open and to closed position to effect opening and closing of the breaker, a safety locking means comprising a normally inoperative locking lever carried by said operating member within said enclosure, said flever being manually settable toa locking position in which it locks saidoperating member in open position.

19. In a multipole circuit breaker having a plurality of pairs of relatively movable contacts forming a plurality of poles, a common operating y mechanism for said contacts including a member releasable to cause opening of all of said pairs of contacts, latch means for releasably restraining said member, an individual trip device for each of at least two of the polesof the breaker, each trip devicecarrying a snap-acting bimetal element that is operable in response to predetermined conditions to effect release of said latch means and opening of the breaker, and movable -means for each trip device for causing movement thereof relative to said/mechanism.

. 20. A circuit interrupter comprising a switch member movable to open and to close the circuit, operating mechanism normally operable to move said switch member in a straight line path to open or to close the circuit, said mechanism includlng a member releasable to cause movement of said switch member to an open circuit position, trip means comprising a snap-acting bimetal element heated in response to the current in said circuit and operable in response to predetermined current conditions to effect release of said releasable member, said bimetal trip elemounted in transverse spaced relation on said base adjacent one end thereof, a common operating mechanism mounted centrally on said base adjacent the other end thereof connected 'to Said movable contacts, said mechanism being manually operable to open ad to close all of said pairs of contacts and including means releasable-to eilect automatic opening of all of said pairs of contacts, the width of said mechanism being less than the width required for the mounting of said plurality of pairs of contacts; and a pair of current responsive release devices mounted 'on opposite sides of said mechanism substantially in transverse alignment with,.a portion thereof, each release device being Operable in response to predetermined overload conditions to eect release of said releasable means.

22. In an enclosed electrical circuit breaker, a casing, an openable cover on said casing, means for locking said cover in closed position on said casing, a circuit breaker mounted in said casing having a movable operating means for opening and closing the breaker thatis operable from outside said casing, and a locking means within said casing manually settable to lock said operating means in one of its operating positions.

23. In an enclosed electrical circuit breaker, a casing, an openable cover on said casing, means for locking said cover in closed position on said casing, a circuit breaker mounted in said casing having a movable operating means for opening and closing the breaker that is operable from outside said casing, and a locking means within said casing manually settable to lock said operating means in' one of its operating positions, said last mentioned locking means being manually settable only when the cover of the casing is open.

24. A circuit breaker comprising a pair of spaced xed contacts, a movable switch element, a cooperating movable bridging contact carried by said switch element, operating mechanism manually operable to cause movement of the switch element and the bridging contact carried thereby in a substantially straight line path to open and to closed position and operable in response to predetermined overload conditions to cause automatic vopening of said contacts, said mechanism comprising an actuating lever connected directly to said switch element and movable to cause movement of the movable contact, an actuating spring connected to the actuating lever for moving said lever, an operating handle manually operable to cause said spring to operate the actuating lever, a pivoted releasable lever engaged by said actuating lever, said releasable lever being urged toward a released position by the force of the spring acting through said actuating lever when the contacts are closed, and

opening of the movable contact irrespective of the position of said handle, and trip means norment being mounted at the side of said operating mechanism.

21. In a multipole circuit breaker, Ia base,J a plurality of pairs ot relatively movable contacts mally preventing movement or the pivoted releasable lever to said released position, said trip means being operable in response to predetermined overload conditions to cause release of said pivoted releasable lever.

LAWRENCE PIERCE.

STEPHAN MILLER, 

